The organic constituents of plants and vegetable substances and their chemical analysis / by G.C. Wittstein ; authorised translation from the German original, enlarged with numerous additions, by Baron Ferd. von Mueller.

  • Wittstein, Georg Christian, 1810-1887.
Date:
1878
Catalogue details

Licence: Public Domain Mark

Credit: The organic constituents of plants and vegetable substances and their chemical analysis / by G.C. Wittstein ; authorised translation from the German original, enlarged with numerous additions, by Baron Ferd. von Mueller. Source: Wellcome Collection.

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    acids. Moschatin is thrown down by addition of water, and the acids by subacetate of lead. Brittle, brown-red, hygroscopic mass of a bitter taste, easily soluble in water, less so in alcohol; in- soluble in ether. Contains nitrogen. Planta Reichenau.] Acids. All organic acids as yet investigated are combinations of carbon with hydrogen and oxygen—seldom without hydrogen, and more seldom still with nitrogen; they have an acid reaction and mostly an acid taste, and form salts with the bases. They are very widely diffused, and it is highly probable that there exists no vegetable organism, which does not contain one or the other; in- deed, experience has shown that many plants contain more than one. They exist very seldom in the free state in the organism, but nearly always either partly or entirely saturated by anorganic or by organic bases (alkaloids); in the event of the basic access being incomplete, they are the cause of the acid reaction of vege- table extracts. The substance found combined with fat acids, and which serves as substitute for bases, is oxyd of glyceryl. Acids are either volatile or not, as in the case of alkaloids. The volatile acids are always obtained by distillation with a fixed mineral acid, preferably phosphoric acid. For fuller information see section ix,, Division III., Part II., where the way of their estimation is also indicated. The particulars for ascertaining, pre- paring and estimating non-volatile acids will be found in sections ii. and viii. The discovery of fat acids coincides in section ii. with the examination of fats. Acolyctin. The root of Aconitum Lycoctonum contains no aconitin, but in its stead two other organic bases, the one of which has been termed Acolyctin, and the other, present in less quantity, Lycoctonin. In order to isolate the Acolyctin, evaporate or distil the alcohol from the tincture (treated beforehand as under Aconitin, according to Geiger and Hesse, first with lime and afterwards with sulphuric acid), remove from the residue—diluted with water, if necessary—all resinous matters, decolourise with animal charcoal, add carbonate of soda in sufficient quantity for a decidedly alkaline reaction and bring to dryness. Grind the substance, extract with chloroform or absolute alcohol, filter, add some water, evaporate to a syruj), shake repeatedly with ether (which dissolves the Lycoctonin), dry and pulverise. Whitish powder of a bitter, not acrid taste, readily soluble in water, in diluted and concentrated alcohol and in chloroform, but not in ether; of alkaline reaction. When ether is added to the alcoholic solution, the whole of it will either be converted into a paste, or the Acolyctin will fall down as a white substance when more diluted. It separates in drops on the bottom of the vessel when ether is added to its solution in chlorofonn. The aqueous solution of the pure Acolj^ctin and of its salts is precipitated by the carbonates of